Mentions:
We have shown that basal AT1R tone restricts skeletal muscle MBV, whereas basal AT2R activity increases muscle MBV (21). We next examined whether selective stimulation of the ANG II subtype receptors by endogenous ANG II regulate insulin-mediated microvascular recruitment. Figure 3 shows the microvascular responses to insulin infusion. Insulin infusion raised plasma insulin concentrations from 99 ± 15 pmol/L to 685 ± 151 pmol/L (n = 5, P < 0.02). As expected, insulin increased both MBV and MBF without altering MFV (Fig. 3). The addition of PD123319 to insulin infusion promptly inhibited this insulin-mediated increase in MBV and MBF and significantly increased the MFV (Fig. 4). When PD123319 was given before insulin infusion, insulin-induced increases in muscle MBV and MBF were completely prevented. On the other hand, infusion of PD123319 after insulin had already significantly recruited muscle microvasculature (i.e., 30 min after insulin infusion) abrogated the insulin effects. These changes did not seem to be secondary to changes in blood pressure or total blood flow because both MAP and FBF remained stable during the study (Table 1). Injection of losartan 5 min prior to the initiation of insulin promptly increased muscle MBV within 30 min, and the extent of the increase (2.4- to 3.2-fold) was quite similar to what we previously observed using losartan alone (21). The increase in MBV lasted for the entire 120 min. Muscle MFV did not change in the first 90 min but decreased at 120 min. As a result, muscle MBF increased promptly at 30 min, remained elevated at 60 min, and trended down afterward (Fig. 5). Though MAP did not change, FBF decreased by nearly 30% (P < 0.01) (Table 1).

Mentions:
We have shown that basal AT1R tone restricts skeletal muscle MBV, whereas basal AT2R activity increases muscle MBV (21). We next examined whether selective stimulation of the ANG II subtype receptors by endogenous ANG II regulate insulin-mediated microvascular recruitment. Figure 3 shows the microvascular responses to insulin infusion. Insulin infusion raised plasma insulin concentrations from 99 ± 15 pmol/L to 685 ± 151 pmol/L (n = 5, P < 0.02). As expected, insulin increased both MBV and MBF without altering MFV (Fig. 3). The addition of PD123319 to insulin infusion promptly inhibited this insulin-mediated increase in MBV and MBF and significantly increased the MFV (Fig. 4). When PD123319 was given before insulin infusion, insulin-induced increases in muscle MBV and MBF were completely prevented. On the other hand, infusion of PD123319 after insulin had already significantly recruited muscle microvasculature (i.e., 30 min after insulin infusion) abrogated the insulin effects. These changes did not seem to be secondary to changes in blood pressure or total blood flow because both MAP and FBF remained stable during the study (Table 1). Injection of losartan 5 min prior to the initiation of insulin promptly increased muscle MBV within 30 min, and the extent of the increase (2.4- to 3.2-fold) was quite similar to what we previously observed using losartan alone (21). The increase in MBV lasted for the entire 120 min. Muscle MFV did not change in the first 90 min but decreased at 120 min. As a result, muscle MBF increased promptly at 30 min, remained elevated at 60 min, and trended down afterward (Fig. 5). Though MAP did not change, FBF decreased by nearly 30% (P < 0.01) (Table 1).